If you can’t spend much, your best bet is this Helmut Lang Romper. It's a great item, while not very pricey. Another strong contender for your wardrobe is this Robert Rodriguez Jumpsuit. While the price of this item is not too high, it will certainly attract a lot of attention. You might also want to consider this Brunello Cucinelli Jumpsuit. The price is very reasonable, but the effect on your wardrobe will be pretty fantastic.